The round pipe partially prevented form radial displacement under internal pressure load, such as the pipe inserted into the tube plate, coupling and flange fitting, is investigated by means of three dimensional photoelasticity. The epoxy resin round pipe model, which is inserted into a circular thick plate, is heated up to the critical temperature in the stress freezing furnace and the internal pressure is maintained constant until the temperature of the inside of the furnace falls to the room temperature.
After stress freezing, the outer diameters of the models are measured and the circumferential stresses produced on the inner and outer surfaces of the models are evaluated by using the many slices obtained from the model. The relationship between the circumferential stresses and the form factors is summarized in the figures. It is shown that in the thin-walled round pipe the maximum outer diameter and the maximum circumferential stress on the outer surface of the round pipe arise on the cross section in the neighborhood of outlet from the thick circular plate. Moreover, the reason for the characteristic results obtained is considered qualitatively.

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The mixed-mode stress intensity factors and the effective stress intensity factors for the corner edge cracks of stepped plate subjected to out-of-plane bending load are evaluated by means of reflective photoelastic experiment. The polycarbonate resin models with silver thin film in the neutral surface are prepared in order to get a good reflection layer, and the cracks with the systematically varied depth and angle are machined on the corner edges.
A large number of the isochromatic fringe patterns taken by means of the CCD camera are recorded in the magneto optical disk, and are transformed into the thinning images of them around the crack tip by using the image processing analyzer. The stress intensity factors are estimated by personal computer using the program based on the over-deterministic method.
The obtained stress intensity factors are summarized in the diagrams shown as the behavior for the variations of crack depth and crack angle. Finally, the results for strip models obtained by this experimental method are compared with the known theoretical ones of the similar problem, and a good agreement between these results are shown. This will assure the the experimental work is appropriate.

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Polarized light has been used on photoelastic experiments, but the expression of polarized light is not clearly defined. And symbols and nomenclature in photoelasticity are also not determined. If the above problems will be clear, the developments of the new methods of the photoelastic analysis and mutual communications between researchers will be promoted easily and fast. We propose an expression method of polarizing light state using Stokes' parameter, and verify its expression by photoelastic photographs using transmitted and reflected equipments.
We find the most suitable symbols and nomenclature from the 95 papers of Proceedings of the Japan Society for Photoelasticity

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The stress intensity factors for the edge crack of a rivet hole in the rivet joint are evaluated by means of photoelasticity. In the ordinary design of rivet joint, the friction between the plates produced by fastening the rivet and the effect upon the plates by the bending deformation of the rivet are neglected. From this standpoint, the photoelastic experiment is carried out using the band plate models with a rivet hole loaded by tension.
The breaking test by acrylic acid resin model is conducted to examine the direction of crack throughout the section of the plate when the breaking occurred. The epoxy resin models are prepared for various form factors; crack depth, crack angle and the distance from the center of rivet hole to plate edge. The isochromatic fringe patterns around the crack tips obtained by the CCD camera are transformed to the thinning image by utilizing the image processing, thus the stress intensity factors are estimated by means of personal computer using the program based on the over-deterministic method. The stress intensity factors obtained are summarized in the diagrams shown as the behavior depending on the form factors.
Moreover, the breaking test using the steel models of rivet joint with three rivet holes in a row is carried out to examine the position of the broken hole. The results are compared with those already obtained photoelastically by authors.

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This study discusses whether finite-element analysis (FEA) is effective for extracting zero points instead of the photoelastic experiment which is generally used. The zero points obtained in several models by FEA are compared with those obtained by a computer-assisted photoelastic experiment. It is difficult to obtain the zero-order isochromatics corresponding to the zero points by FEA. The zero-order isochromatics are therefore determined as follows. First, the lowest isochromatic which is as near as possible to the zero-order one is found. Second, to confirm the existence of the zero-order isochromatic in the zone surrounded by the lowest one, it is compared with the zero-order one obtained by the experiment. If the lowest isochromatic is superimposed on the experimental zero-order one, the center of the zone is judged to correspond to the zeroorder one. Finally, the center corresponding to the zero point is determined by the naked eye. Consequently, FEA in combination with the photoelastic experiment is found to be more convenient for extracting the zero points than the experiment alone.

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This paper discusses how to describe the state of polarization of light propagating through a photoelastic model by the retarders model approximation. The approximation is applied to a description of the polarization state along a light path in the case of a uniforrn rotation of the secondary principal axes. The dependence of the polarization state on the number of divisions of the path into small sections is illustrated.

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The quarter wave plate in the Senarmont's compensator satisfies only for a monochromatic light. And the retardation in a test piece is obtained by the Senarmont's compensator as the fraction of total fringe order. In order to resolve this problem, the composite quarter wave plate has been developed. A trial equipment of automatic retardation tester is made up with the composite quarter wave plate in accordance with Senarmont's compensator. Complicated calcuration and setting of the azimuth angles of each plates is made automatically by a computer and steppingmotors. And the measurement of the retardation in a test piece is also carried out easily by it. Using this equipment, the absolute retardation in the test piece can be also obtained easily and precisely for each wave length.

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